[regallocfast] Make sure the MachineRegisterInfo is aware of clobbers from a
register masks.  This is an obvious and necessary fix for a soon to be committed
patch.  No test case possible at this time.  Reviewed by Jakob.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167498 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index e426fe2..8892216 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -956,6 +956,11 @@
     bool hasPhysDefs = false;
     for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
       MachineOperand &MO = MI->getOperand(i);
+      // Make sure MRI knows about registers clobbered by regmasks.
+      if (MO.isRegMask()) {
+        MRI->addPhysRegsUsedFromRegMask(MO.getRegMask());
+        continue;
+      }
       if (!MO.isReg()) continue;
       unsigned Reg = MO.getReg();
       if (!Reg) continue;